After 3 years of happy sand filter ownership, out of boredom I finally got around to adding DE to my sand filter.
My water was really clear but I wanted to play around. I got harassment from a buddy of mine who said that my water was great so why bother. Leave it alone!
I backwashed and rinsed, then added 1.5 cups of DE to my 1,600 gph filter. The psi went up about 1 psi or so, per instructions.
Wow. It only took 5 hours of operation to bring the output to barely anything. There was so little flow that I was amazed. Flow was probably 10% of normal. The clarity of the water was amazing. I backwashed again and I was back in business.
I will do it again for sure. Not something I will do all the time, just something I will do on occasion.